/**
 * @(#)YcsFileUtils.java, 2021/12/22.
 * <p/>
 * Copyright 2021 Netease, Inc. All rights reserved.
 * NETEASE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package site.ycsyxt.common.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * 文件操作相关工具类
 *
 * @author ycs(15241496739 @ 163.com)
 * @date 2021/12/26
 **/
public class FileUtils {
    /**
     * 文件系统主要由inode和block组织。一个block一般4K大小，即使写入1字节到文件，文件所占大小也是4K
     * <p>
     * 详见：https://mp.weixin.qq.com/s?__biz=MjM5Njg5NDgwNA==&mid=2247487146&idx=1&sn=2786cd64da86d3d3c976ec8ddf0cbbf8&chksm=a6e30f91919486871b7e3e2530e8915a6d9034de905fcd81d9b673ac2d5b745f84dee936e9a8&cur_album_id=1371808335259090944&scene=189#wechat_redirect
     */
    public static final int BLOCK = 4 * 1024;

    /**
     * 读取文件的byte数组到输出流
     *
     * @param filePath 文件路径 + 文件名
     * @param os       输出流
     * @return
     */
    public static void readBytes(String filePath, OutputStream os) {
        try (FileInputStream fileInputStream = new FileInputStream(filePath)) {
            byte[] b = new byte[BLOCK];
            int length;
            while ((length = fileInputStream.read(b)) > 0) {
                os.write(b, 0, length);
            }
        } catch (IOException e) {
            throw new RuntimeException("读取文件的byte数组到输出流失败！filePath = " + filePath + "\n" + e);
        }
    }

    /**
     * 写入byte数组数据到文件中
     *
     * @param data     数据
     * @param filePath 文件路径 + 文件名
     * @return 目标文件
     */
    public static void writeBytes(byte[] data, String filePath) {
        try (FileOutputStream outputStream = new FileOutputStream(filePath)) {
            outputStream.write(data);
        } catch (IOException e) {
            throw new RuntimeException("写入byte数组数据到文件中！filePath = " + filePath + "\n" + e);
        }
    }

    /**
     * 删除文件
     *
     * @param filePath 文件路径 + 文件名
     * @return
     */
    public static boolean deleteFile(String filePath) {
        boolean flag = false;
        File file = new File(filePath);
        // 路径为文件且不为空则进行删除
        if (file.isFile() && file.exists()) {
            file.delete();
            flag = true;
        }
        return flag;
    }

    /**
     * 获取文件名后缀
     * <p>
     * 例如: xxx.txt, 返回: txt
     *
     * @param fileName 文件名
     * @return （不含".")
     */
    public static String getFileType(String fileName) {
        int separatorIndex = fileName.lastIndexOf(File.separator);
        if (separatorIndex < 0) {
            return "";
        }
        return fileName.substring(separatorIndex + 1).toLowerCase();
    }

    /**
     * 获取文件真实类型
     *
     * @param photoByte 文件字节码
     * @return 后缀（不含".")
     */
    public static String getFileExtendName(byte[] photoByte) {
        if ((photoByte[0] == 71) && (photoByte[1] == 73) && (photoByte[2] == 70) && (photoByte[3] == 56)
                && ((photoByte[4] == 55) || (photoByte[4] == 57)) && (photoByte[5] == 97)) {
            return "gif";
        }

        if ((photoByte[6] == 74) && (photoByte[7] == 70) && (photoByte[8] == 73) && (photoByte[9] == 70)) {
            return "jpg";
        }

        if ((photoByte[0] == 66) && (photoByte[1] == 77)) {
            return "bmp";
        }

        if ((photoByte[1] == 80) && (photoByte[2] == 78) && (photoByte[3] == 71)) {
            return "png";
        }

        throw new RuntimeException("获取文件真实类型失败！");
    }
}
